Suspect 1 Manssour Arbabsiar, 56, moved from Iran to the US in the 1980s and disappeared into the suburbs of Corpus Christi, Texas, where, according to reports, his friends knew him as "Jack". He was unremarkable, working for a while in a used car lot and seeming to get along with his neighbours in the quiet cul-de-sac. In recent years, business frequently took him across the border to Mexico – a fact that allegedly piqued the interest of a cousin in Iran, Abdul Reza Shahlai, who is a member of the Iranian Revolutionary Guard's elite al-Quds force. Shahlai is said to have introduced him to a second member of the Quds force, Gholam Shakuri, who is alleged to have asked Arbabsiar to contact a drug cartel and arrange the hit. There is nothing immediately apparent to suggest Arbabsiar was essential to the plot – except perhaps that he was so nondescript.

Suspect 2 Gholam Shakuri is allegedly a member of the Quds force. The foreign arm of Iran's Revolutionary Guard, it operates with the same discipline and zeal as the Lebanese Hezbollah, a group which it has mentored and backed for 29 years. Quds members are rarely publicly identified. They are obsessive about the secrecy of their operations and leadership. Shakuri seemed to be a man in a hurry when he talked to Arbabsiar on the telephone. It is not the type of breach that would please his superiors, especially Quds Force leader, Qassem Suleimani.

The alleged mastermind Qassem Suleimani is one of the most powerful and feared men in the Middle East. His power and authority come straight from Iran's theological leader, Ayatollah Ali Khamenei, bypassing President Mahmoud Ahmadinejad, who has little of Suleimani's influence. He has been particularly active during the past five years, using his trademark mix of aggressive military operations and strategic diplomacy to stamp Iran's authority on Iraq, Lebanon, Syria, Afghanistan and Gaza. His successes have been many and his failings few. If this indeed was a Quds plot gone publicly wrong, it would be one of the first.

The target Adel al-Jubair is a staunch critic of Iranian influence in the Arab world and a key ally of Saudi Arabia's monarch, King Abdullah. Both have complained regularly to the US and Sunni Arab states about the rise of the "Persians" – previously described by Jubair as the "head of the snake", according to a WikiLeaks cable. Educated in the US, Jubair has been Saudi Arabia's ambassador to Washington for almost five years. He has done much to consolidate US-Saudi strategic ties, using the spectre of a mutually feared nuclear-powered and expansionist Iran as a key bargaining tool.